feat: shared supervisor timeline, story assignment and time-spiral view

Each source version is extracted once for every review scope; events carry spans and projects from their sources, and attention density is counted from messages. After publication, events are assigned to project features and sub-threads (cross-project stories only when enabled), with user rename, merge, remove, move and undo. The story graph gains a lazily loaded Three.js time-spiral view. Includes the 3D concept demo, real-data DeepSeek check scripts and docs.

src/preload/index.ts

@@ -1425,7 +1425,10 @@ const desktopApi: DesktopApi = {
     relationAction: (input) => ipcRenderer.invoke(ipcChannels.supervisionRelationAction, input) as Promise<void>,
     suggestions: (input) => ipcRenderer.invoke(ipcChannels.supervisionSuggestions, input ?? {}),
     suggestionAction: (input) => ipcRenderer.invoke(ipcChannels.supervisionSuggestionAction, input),
-    retrySuggestions: (input) => ipcRenderer.invoke(ipcChannels.supervisionRetrySuggestions, input)
+    retrySuggestions: (input) => ipcRenderer.invoke(ipcChannels.supervisionRetrySuggestions, input),
+    stories: (input) => ipcRenderer.invoke(ipcChannels.supervisionStories, input),
+    storyAction: (input) => ipcRenderer.invoke(ipcChannels.supervisionStoryAction, input) as Promise<void>,
+    retryStories: (input) => ipcRenderer.invoke(ipcChannels.supervisionRetryStories, input)
   },
   experts: {
     list: () =>